TfW replaced the previous franchise, Arriva Trains Wales in October 2018.

On 16 July 2012 plans to electrify the line were announced by the Government as part of a £9.4bn package of investment of the railways in England and Wales.

[3] The announcement was made as an extension of the electrification of the South Wales Main Line from Cardiff to Swansea and the electrification of the south Wales Valley Lines at a total cost of £350 million.

The investment will require new trains and should result in reduced journey times and cheaper maintenance of the network.

[4][5] However, as part of Welsh Government's South Wales Metro this line has been taken over,[6] and will soon be electrified[7] in preparation for new Class 756 rolling stock.